Electrogenerated chemiluminescence sensor for the determination of metoclopramide using ordered mesoporous carbon for immobilizing tris(2,2'-bipyridyl)ruthenium

A novel electrogenerated chemiluminescence(ECL)sensor for the determination of metoclopramide was developed by employing ruthenium complex as an ECL signal producer and an ordered mesoporous carbon(OMC)material as modified material.The ECL sensor was fabricated by adsorption ruthenium complex into a mixture of OMC and Nafion,which showed good electrochemical and ECL behaviors.It was found that the ECL intensity of the sensor fabricated was greatly enhanced in the presence of metoclopramide.Based on this finding,a highly sensitive and reproducible ECL method was developed for the determination of metoclopramide.The result showed that the ECL intensity was linear with the concentration of metoclopramide in the range from 1.0×10-10 to 5.0×10-7M and the detection limit was 3×10-11M.The ECL sensor exhibited a long-term stability and a fine reproducibility with relative standard deviation of 1.0 % for 1.0×10-10M metoclopramide in 18 continuous determinations.The developed method has been applied to the determination of metoclopramide in tablet samples with satisfactory results.

Flow Injection Analysis of Histidine with Enhanced Electrogenerated Chemiluminescence of Luminol

A simple and sensitive flow injection method is presented for the determination of histidine based on its enhancement of electrogenerated chemiluminescence (ECL) of luminol. After optimization of the experimental parameters, the working range for histidine was in 1.0 x 10-6 to 1.0 x 10 -3 mol/L with a detection limit (S/N = 3) of 0.56 mmol/L. The relative standard deviation was 1.6% for 11 measurements of 5 x 10 5 mol/L histidine solution. The proposed method has been successfully applied to the determination of histidine in real pharmaceutical preparation.

Blue Electrogenerated Chemiluminescence from Halide Perovskite Nanocrystals

Electrogenerated chemiluminescence(ECL)has been extensively used in ultrasensitive electroanalysis because it can be generated electrochemically without using expensive optics and light sources.Visible ECL emission can be obtained with a reasonable quantum yield and stability.Blue ECL is rare and often suffers from stability and poor quantum efficiency.Blue ECL emission at 473 nm from organometallic halide perovskite nanocrystals(PNCs),CH_(3)NH_(3)PbCl_(1.08)Br_(1.92),is reported here for the first time using tripropylamine(TPrA)as co-reactant.The blue ECL emission peak resembles its photoluminescence peak position.In addition to this blue emission peak,the ECL spectra of CH_(3)NH_(3)PbCl_(1.08)Br_(1.92) PNCs also showed a broad ECL peak at 745 nm.Generation of the second ECL peak at 745 nm from CH_(3)NH_(3)PbCl_(1.08)Br_(1.92) PNCs was can be explained by the existence of surface trap states on as-synthesized PNC due to incomplete surface passivation.Halide anion tunability of ECL emission from CH3NH3PbX3(X:Cl,Br,I)PNCs is also demonstrated.The fluorescence microscopy image of single PNC and stability of selected single PNCs are presented in this with simultaneous acquisition of fluorescence spectra using 405-nm laser excitation.The photoluminescence(PL)decay was described by PL lifetime(τ)of 1.2 ns.The effect of the addition of surfactants(oleic acid and n-octylamine)on the fluorescence intensity and stability of CH_(3)NH_(3)PbCl_(1.08)Br_(1.92) PNCs is also discussed.

A Novel Electrogenerated Chemiluminescence Reaction Scheme Using Core-Shell LuminoI-Based SiO2 Nanoparticles as a Regulator and Its Analytical Application

A novel core-shell luminol-based SiO2 nanoparticle While these nanoparticles were used as electrogenerated was synthesized by two step micro-emulsion method. chemiluminescence （ECL） reagent, the electrochemical （EC） reaction as well as the subsequent chemiluminescence （CL） reaction not only could be separated spatially, but also presented high efficiency for analytical purpose. In this case, the core-shell luminol-based SiO2 nanoparticles offered more potential to avoid the contradiction between the EC and the CL reaction conditions. A new ECL method based on the nanoparticle was developed, and isoniazid was selected as a model analyte to illustrate the characteristics of this new ECL method. Under the selected conditions, the proposed ECL response to isoniazid concentration was linear in the range of 1.0 ×10^-10 to 1.0 × 10^-6 g/mL with 2 × 10^-11g/mL detection limit.

Electrogenerated chemiluminescence aptasensor for thrombin incorporating poly(pyrrole-co-pyrrole propylic acid) nanoparticles loaded with aptamer and ruthenium complex

A novel electrogenerated chemiluminescence （ECL） aptasensor for highly sensitive detection of thrombin was developed on the basis of poly（pyrrole-co-pyrrole propylic acid） nanoparticles loaded with aptamer and ruthenium complex. Thrombin binding aptamers served as the molecular recognition elements and ruthenium bis（2,2＇-bipyridine） （2,2＇-bipyridine-4,4＇-dicarboxylic acid）-ethylenediamine （Rul） was used as an ECL signal complex. Novel electroactive polymers poly（pyrrole-co-pyr- role propylic acid） nanoparticles （Ppy-pa NPs） were synthesized by a simple alcohol-assisted microemulsion polymerization. Rul-Ppy-pa NPs were synthesized by covalently coupling Rul with the Ppy-pa NPs. Ppy-pa NPs and Rul-Ppy-pa NPs were characterized using a fourier transform infrared spectrometer, super-conducting fourier digital NMR spectrometer, and trans- mission electron microscope. One ECL chemical sensor fabricated by immobilizing the Rul-Ppy-pa NPs on PIGE was developed for the determination of TprA with a high sensitivity and stability. The ECL aptasensor was fabricated by covalenfly coupling the thrombin binding aptamer-I （TBA-I） onto the surface of the paraffin-impregnated graphite electrode, which had been covalently modified with a monolayer of 4-aminobenzene sulfonic acid via electrochemical oxidations, for capturing thrombin onto the electrode and then the TBA-II labeled with Rul-Ppy-pa NPs was bound with epitope of thrombin. The ECL aptasensot showed an extremely low detection limit of 3.0×10^-16 mol/L for thrombin and a good selectivity. This work demonstrated that using Ppy-pa NPs as a carrier of ruthenium complex and molecular recognition element was a promising approach for the fabrication of ECL biosensor with high sensitivity.

Towards Determining Kinetics of Annihilation Electrogenerated Chemiluminescence by Concentration-Dependent Luminescent Intensity

In ion-annihilation electrochemiluminescence(ECL),luminophore ions are generated by oxidation as well as reduction at electrodes surfaces,and subsequently recombine into an electronically excited state,which emits light.The intensity of the emitted light is often limited by the kinetic rate of recombination of the luminophore ion species.Recombination or annihilation rates are high ranging up to approximately 10^(10) M^(−1) s^(−1) and can be difficult to determine using scanning electrochemical microscopy or high-frequency oscillations of an electrode potential.Here,we propose determining annihilation kinetics by measuring the relative change of the emitted light intensity as a function of luminophore concentration.Using finite element simulations of annihilation ECL in a geometry of two closely spaced electrodes biased at constant potentials,we show that,with increasing concentrations,luminescence intensity crosses over from a quadratic dependence on concentration to a linear regime-depending on the rate of annihilation.Our numerical results are applicable to scanning electrochemical microscopy as well as nanofluidic electrochemical devices to determine fast ion-annihilation kinetics.

Electrochemiluminescence Imaging Techniques for Analysis and Visualizing

Electrochemiluminescence(ECL)-based imaging analysis is a dominant method to inspect the electrode composition,to study electrochemical reaction kinetics at a microscopic level,and also a rapid emerging technology in bioanalysis with high spatiotemporal resolutions,high-throughput and visualization characteristics.In comparison with other imaging microscopes,an optical excitation is not involved in imaging,thus the approach is free from background noise resulting in a low detec-tion limit.In this review work,the principle of ECL,its unique natures compared to other luminescence techniques were briefed at first.Then after,the progress and basic principles of ECL imaging were summarized.Furthermore,recent and representative advances of ECL imaging for visualizing and sensing applications were reviewed.Finally,the perspectives in ECL imaging for further perspective were discussed.

Flow-Injection Electrochemiluminescence Detecting Rifampicin Based on Its Sensitizing Effect

MA, Hong Yana,b( ZHENG, Xing-Wanga ZHANG, Zhu-Jun*,aa College of Chemistry and Material Science, Shaanxi Normal University, Xi′an , Shaanxi 710062, China b College of Chemistry and Chemical Engineering, Provincial Key Laboratory of Chemical Reaction Engineering, Yan′an University, Yan′an, Shaanxi 716000, China A new flow-injection electrogenerated chemiluminescence (ECL) method for the determination of rifampicin was developed. The method is based on the sensitizing effect of rifampicin on the weak ECL signal of electrochemical oxidation of luminol on the surface of the platinum flake electrode in the medium of 0.02 mol·L-1 Na2B4O7. This ECL response is in the range of 1.0×10-84.0×10-6 mol·L-1 rifampicin with a detection limit of 8.0×10-9 mol·L-1. The relative standard deviation is 1.8%. This method has been applied successfully to the determination of rifampicin in capsule, ocustilla and urine samples.

Chemical Measurement and Analysis: from Phenomenon to Essence

The review summaries our achievements in optical,electrochemical,as well as mass spectrometry analysis and imaging with high sensitivity,specificity,and spatiotemporal resolution.We promoted the plasmonic imaging system,and developed ultra-sensitive plasmonic nanoprobes for the tracking of single molecules in single living cells,as well as plasmonic nanocatalysts for highly efficient energy conversion.In addition,we contributed a lot in electrogenerated chemiluminescence(ECL)analysis and imaging.Pioneering works including localized surface plasmon resonance(LSPR)enhanced ECL,ECL ratiometric detection,BPE based ECL system,multi-color ECL sensing as well as super-resolved ECL imaging have been initiated by our group.Furthermore,we also dedicated in nanopipette based electrochemical analysis in single living cells,as well as ESI-MS analysis on short time scale.

Visual Voltammogram at an Array of Closed Bipolar Electrodes in a Ladder Configuration

In this paper,we report a method for obtaining a visual voltammogram at a linear array of closed wireless bipolar electrodes(BPEs).This advancement is significant,because the visual voltammogram captures the entire current-potential(i-E)relationship of a faradaic reaction in one image and is continuously generated over time.Therefore,we anticipate that this method will allow monitoring in redox systems that change over time.Further,the use of a linear array of BPEs eliminates the need to use a potentiostat and can be carried out with a simple DC power supply.Our experimental and numerical results demonstrate that the visual voltammogram is similar to a linear sweep voltammogram and therefore,information about the faradaic process can be extracted from the wave position,height,and shape.